Variable speed transmission



Jan. 23, 1940. 'r. B. MARTIN VARIABLE SPEED TRANSMISSION Filed Oct. 1,1937 2 Sheets-Sheet 2 I INVENTOR.

J/wrnas AB. mam :m

.16 It is a further object to provide such a device driven shaft H inposition to mesh with the pin- Patented Jan. 23. 1946 K 3 UNITED STATESPATENT" OFFICE VARIABLE SPEED TRANSMISSION Thomas B. Martin, Ithaca, N.Y., assignor, by mesne assignments, to Bendix Aviation Corporation,South Bend, Ind., a corporation of Delaware Application October 1, 1937,Serial No. 166,844

11 Claims. (.01. 74-368) The present invention relates to a variableabutting against a thrust collar I6 bearing on speed transmission andmore particularly toa rethe inside of the plate 5. Motion of the drivenduction gearing having two optional gear ratios shaft to the left inFig. 1 is resisted by yielding particularly adapted for automatic orsemi-automeans in the form of a ball I! slidably'mounted matic operationas, for instance, in connection in a recess I B in the end of the drivenshaft, 5 with domestic laundry appliances. bearing against a thrustplate l9 seated in the It is an object of the present invention toproend of the bearing l2. A spr 2| Seated in t vide a novel variablespeed transmission incorrecess I 8 serves to press the ball I! againstthe porating hydraulic controlling means for the thrust plate 9 a d t ey yieldingly maintain 10 gearing. the driven shaft in its normalposition with the 10 It is another object to provide such a devicethrust ring I4 bearing on the collar l6. in which the power foroperating the controlling A low speed transmission between the powermeans is derived from the operation of the transshaft 2 and the drivenshaft I I is provided in the Fmission itself. form of a low speed gear22 journalled on the incorporating meansfor automatically controlionmember I and connected to.drive the driven ling the torque transmittedtherethrough. shaft by means of an overrunning clutch. As It is anotherobject to provide such a device] ere shown, the overru clutch c ude a inwhich the high speed transmission includes a disc member 23 threaded ona hollow shaft 24 friction clutch with means for automatically keyed asindicated at 25jto the driven shaft. 20 limiting the torque transmittedtherethrough to The pitch of the threads on shaft 24 is such asa'predetermined maximum. to move the clutch member '23 into engagementFurther objects and advantages will be apwitha cooperating clutchsurface 26 on the driven parent from the following description taken ingear 22 when the clutch member 23 overruns 25 connection with theaccompanying drawings in the screw shaft 24. Means for causing such 25which: engagement of the clutch member 23 is provided Fig. 1 is avertical substantially mid-sectional in the form of a friction ringmember 21 slidably view; mounted in a groove on the periphery of theFig. 2 is a detail illustrating the gear pump and clutch member andconnected to rotate with the 30 operating mechanism therefor; gearmember 22 by suitable means such as indi- 30 Fig. 3 is an end elevation'of the device partly cated at 28.

in section, the section being taken substantially A high speedtransmission between the power on the line 3-3 of Fig. 1; and shaft 2and the driven shaft II is provided in the Fig. 4 is a detail in sectionshowing the relief form of a high peed gear 29 jellrnaled 0n the valvecontrolled by longitudinal movement of pinionmember 1 and arranged tomesh with a 35 the driven shaft.- high speed driven gear 3| keyed asindicated at Referring first to Fig. 1 of the drawings, there 32 on thedriven shaft. Means for transmitting is illustrated a casing l of amotor, not further rotation from the pinion member I to the highillustrated. A power shaft 2 which may be the speed drivinggear 29 isprovided in the form of 4o armature shaft of said motor is journalled at3 a high speed clutch indicated generally by nuin the casing and extendsout into a gear hous- I meral 33. ing 4 formed as a generally cup-shapedextension According to the present invention, means of the casing I.Thehousing 4 is closed by a under the control of the operator areprovided plate member 5 suitably attached thereto as by for closing andrelaxing the high speed clutch 33 means of cap screws 6. A quill shaftand low in order to operate the driven shaft optionally i1. 5 speedpinion member I is arranged at one end to' high or low gear with respectto the power shaft fit over the end of the power shaft 2 and be 2. Forthis purpose the clutch 33 is formed with connected to rotate therewithas by means of a a barrel member 34 suitably fixed to the high key 8.The outer end of the pinion member 1 is speed drive gear 29, and aseries'of friction discs. journaled in the plate 5 as indicated at 3. A35 and 36 are spiined alternately to the barrel to driven shaft H isjournalled at l2 in the casing 34 and the periphery of the quill shaftand pinion l and at 13 in the plate 5, with provision for lonmember I.The pack of clutch discs 35,, 36 is gitudinal movement in said Journals,movement arranged to bear against a thrust plate 37 seated to the rightbeing limited by a split thrust ring against a shoulder 38 on the end ofthe quill l4 seated in a groove IS in the driven shaft and shaft andpinion member 7, and means are pro- 5s vided for compressing the clutchdiscs thereagainst in the form of a piston member 39 slidably mounted inthe barrel 34 in position to bear against the clutch pack and actuatedto that effect by fluid pressure under the control of the operator.

The fluid pressure for operating the clutch is derived from theactuation of the transmission by means of a gear pump formed by a pairof intermeshing gears 4| and 42 (Fig. 2) rotatably mounted in a pumphousing 43 attached to or formed in the gear housing 4 in position to beimmersed in the lubricant contained in said housing. Gear 42 is arrangedto mesh with the driving pinion member I so that the pump members rotateconstantly during the operation of the transmission.

Means for transmitting the lubricant under pressure from the gear pump4|, 42 to the high speed clutch barrel 34 is provided in the form ofconduits 44 and 45 in the closure plate 5, groove 46 in the periphery ofthe pinion member I registering with the conduit 45, radial openings 4'!intersecting the groove, and a conduit 48 traversing the quill shaft andpinion member I and connected by radial openings 49 with the interior ofthe barrel 34.

A by-pass valve for the fluid is provided in the form of a ball 5|bearing against and normally closing the open end of the conduit 48 inthe pinion member I, being held thereagainst by a spring 52 actuated bythe plunger 53 of a solenoid 54. It will be understood that the solenoid54 is energized in any suitable manner under the control of the operatorso as to close the by-pass and thus cause closure of the high speedclutch 33 when high speed operation of the transmission is desired. Theoverflow from the by-pass valve 5| is conducted by a conduit 55 in theplate 5 back to the interior of the housing.

Means are provided for automatically limiting the torque to betransmitted by the high speed clutch, such means comprising a reliefvalve in the form of a port 56 (Fig. 4) connected by a conduit 51 to theconduit 45 and normally closed by a ball 58 which is retained inposition by a yielding plate member 59.

The retaining plate 59 is moved in a direction to maintain the reliefvalve closed by engagement with a member mounted on the driven shaftwhereby the yielding pressure of the spring 2| on the driven shaft istransmitted to the plate member 59 to close the relief valve. As hereillustrated, the member on the drivenshaft which engages the platemember 59 is the driven gear 22, but it will be understood that anyother arrangement may be used whereby the force of the spring 2| on thedriven shaft is transmitted to the plate 59- to close the relief valve.

Load-controlled means for opposing the action of the spring 2| andpermitting the relief valve to open is provided by forming the teeth ofthe high speed gears 29, 3| with a suitable helical inclination wherebythe transmission of torque to the driven gear 3| is accompanied by alongitudinal component tending to move the driven shaft II to the leftin Fig. 1 against the action of spring 2|. It will be understood thatthe stiffness of spring 2| is so chosen in conjunction with the helicalangle of the high speed driving gears that the relief valve will bepermitted to open when the maximum desirable torque through the highspeed gears is exceeded. The spring 2| may, of course, bereadily-adjusted by inserting spacers below the spring in the recess |8.

In the operation of the device, and considering first the condition whenthe solenoid 54 is deenergized so that the by-pass valve 5| is loose,energization of the power shaft 2 causes rotation of the quill shaft andpinion member I which rotates the low speed driven gear 22, causing theoverrunning clutch 23, 26 to close and transmit rotation to the drivenshaft H at low speed. At this time, lubricant from the housing is pumpedby the gears 4|, 42 through conduits 44, 45 to the conduit 48 in theinterior of the pinion member The lubricant is allowed to escapetherefrom without generating appreciable pressure, however, by reason ofthe open condition of the by-pass valve 5| which permits the lubricantto return to the interior of the housing through the conduit 55.

When it is desired to operate the transmission in high gear, theoperator causes energization of the solenoid 54, thus closing theby-pass valve 5|, whereupon the lubricant pressure is transmittedthrough conduit 48 and openings 49 to the interior of the clutch barrel34 where it acts on the piston 39 to compress the clutch discs 35, 36against the thrust plate 31 and thereby connect the high speed gear 29for rotation with the power shaft 2. The rotation of gear 29 istransmitted through the driven high speed gear 3| to the driven shaft Hto rotate it at high speed, causing the clutch 23, 26 to overrun.

If the torque transmitted during acceleration of the driven shaft by thehigh speed gearing reaches a predetermined maximum, the longitudinalcomponent produced by the helical arrangement of the teeth becomessufficient to overcome the spring 2| and move the driven shaft more orless to the left, thus permitting the relief valve 58 to open more orless and relieve the hydraulic pressure in the clutch operating system.The high speed clutch 33 is thus permitted to slip and partially relievethe load on the transmission. As soon as the unusual resistance torotation of the driven shaft has been overcome, the reduction in thetorque transmitted through the high speed gearing permits the drivenshaft to be returned to its normal position by the spring 2| whereby therelief valve 58 is closed and the high speed clutch 33 caused to operatewithout slipping.

When it is desired to return to low speed drive, it is merely necessaryfor the operator to cause deenergization of the solenoid 54, whereuponthe by-pass valve 5| is permitted to open, thus relaxing the high speedclutch 33 and permitting the low speed clutch 23, 26 to pick up anddrive the driven shaft at low speed.

Although but one embodiment of the invention has been shown anddescribed in detail, it will be understood that other embodiments arepossible and various changes may be made in the design and arrangementof the parts without departing fromthe spirit of the invention asdefined in the claims appended hereto.

What is claimed is:

, 1. Transmission means including a gear train and a friction clutch,fluid-pressure means for "closing said clutch, and torque-responsivemeans for relieving the fluid pressure to thereby limit .thetransmission of torque through the gear train.

. 2. Transmission means including helical gearing and a friction clutch,fluid-pressure means .for closing the clutch, and means actuated by aated by the torque transmitted through the high speed gear train .forcontrolling said relief valve.

4. In a variable speed transmission, a low speed gear train including anoverrunning clutch, a high speed gear train including a friction clutch,closing means for said friction clutch including a source of fluidpressure and means for conducting and applying said pressure to closethe clutch, a relief valve for said pressure, yielding means normallyholding said relief valve closed,

and means responsive to the torque transmitted through the high speedgearing for overcoming said yielding means and relaxing said valve.

5. In a variable speed transmission, an oil-tight housing, gearingmounted therein including a gear connection comprising a normally openfriction clutch, and means for closing the clutch including a fluid pumpin the housing driven from the transmission, means for conducting fluidunder pressure from the pump and utilizing it to close the clutch, aby-pass for said fluid, and means responsive to the torque transmittedthrough the gear connection for opening and closing said by-pass.

6. In a variable speed transmission, an oil-tight housing, gearingmounted therein including constantly rotating low speed gearing, a fluidpump in the housing driven by the gearing, high speed gearing includinga hydraulically controlled friction clutch, means for conducting fluidunder pressure from the pump to said clutch, a relief valve forpermitting the fluid to escape into the casing, and means responsive tovariations in load on the high speed gearing for controlling the openingof the relief valve.

7. In a variable speed transmission; a power shaft,'a driven shaft, alow speed gear train therebetween including a pinion member connected torotate with the power shaft, and a gear having an overrunning clutchconnection with the driven shaft, a high speed connection between theshafts including a friction clutch, a gear pump actuated from the powershaft, means for I transmitting fluid under pressure from the pump andutilizing said fluid to close the clutch, a bypass valve for said fluid,and means responsive to the torque transmitted through the gearing forcontrolling said valve.

en shaft caused by the transmission of a predequill shaft, clutch discsin the barrel splined al- 8. In a variable speed transmission, a powershaft, a helical driving gear, a friction clutch for connecting the gear'to the shaft, a source of fluid pressure actuated from the power shaft,.means for conducting and applying said pressure to close the clutch, apressure-relief valve for said conducting means, a driven shaft, ahelical driven gear fixed thereon meshing with the drive gear, meansmovable by the driven shaft for holding said valve closed, and yieldingmeans for biasing the driven shaft into valve-closing position, theinclination of the teeth of the gears being such that r the transmissionof torque therethrough causes an end thrust on the driven shaft opposingsaid yielding means.

9. In a variable speed transmission, a power shaft, a helical drivinggear, a friction clutch-for connecting the gear to the shaft, a sourceof fluid pressure actuated from the power shaft, means for conductingand applying said pressure to close the clutch, a pressure-relief valvefor-said conducting means, a driven shaft, a helical driven gear fixedthereon meshing with the drive gear, and means whereby the axial thruston the drivterminedtorque through said gears'causes the relief valve toopen and reduce the pressure on the clutch.

10. In a variable speed transmission, a drive shaft, a hollow quillshaft and driving clutch member splined thereon, a gear and drivenclutch member in the form of a barrel joumalled on the quill shaft,clutch discs in the barrel splined alternately to the quill shaft andbarrel, means including a piston slidably mounted in the barrel forcompressing the discs, means for supplying fluid under pressure throughsaid quill shaft to the interior of the barrel to actuate the piston,and means responsive to torque transmitted by said gear for regulatingthe pressure of said fluid.

11. In a variable speed transmission, a drive shaft, a hollow quillshaft and driving clutch member splined thereon, a gear and drivenclutch member in the form of a barrel journalled on the ternately to thequill shaft and barrel, means including a piston slidably mounted in thebarrel for compressing the discs, means including a pump driven by thequill shaft for supplying fluid under pressure through the quill shaftto the in- 1 terior of the barrel to actuate the piston, by-pass meansfor relieving the pressure of said fluid, means under the control of theoperator for closing the by-pass means, and means responsive to torquetransmitted by said gear for regulating t the pressure of said fluid.

THOMAS B. MAR'ITN.

